Recently, printing methods, which are superior in terms of productivity and manufacturing costs, have been used for forming electrode patterns or wiring patterns for various types of electronic devices, such as touch panels, touch sensors, membrane switches, and organic electroluminescence devices. Among these methods, gravure offset printing has attracted attention due to its suitability for forming high-precision patterns.
Patent Literature 1 describes a case in which a touch sensor is formed by gravure offset printing. FIGS. 1 and 2 show a structure of a touch key having the touch sensor and a gravure offset printing machine used for manufacturing the touch sensor, which are described in Patent Literature 1.
As shown in FIG. 1, the touch key includes a touch sensor 10 and a touch-sensor driving circuit 15. The touch sensor 10 includes a substrate 11, net-like electrodes 12 formed on the substrate 11, outer-edge wiring lines 13 provided at outer edges of the net-like electrodes 12, and connection wiring lines 14 for connecting the outer-edge wiring lines 13 to the touch-sensor driving circuit 15. The net-like electrodes 12 are in the form of meshes. The outer-edge wiring lines 13 extend along the upper sides of the net-like electrodes 12 in FIG. 1.
The net-like electrodes 12, the outer-edge wiring lines 13, and the connection wiring lines 14 are printed on the substrate 11 at the same time by using the gravure offset printing machine and are then cured.
As shown in FIG. 2, a gravure offset printing machine 20 includes a plate table 21, a base-member table 22, a doctor blade 23, a transfer roller 24, a device frame 25, and a dispenser (not shown). An intaglio plate (gravure plate) 27, where intaglio patterns 26 having a net-like intaglio portions 26a, outer-edge intaglio portions 26b, and connection intaglio portions 26c corresponding respectively to the net-like electrodes 12, the outer-edge wiring lines 13, and the connection wiring lines 14 of the touch sensor 10 are formed, is placed on the plate table 21 and secured thereto. The substrate 11, which is a member on which printing is performed, is placed on the base-member table 22 and secured thereto. The doctor blade 23 and the transfer roller 24 are both movable along the X-axis and the Z-axis. The dispenser is also movable along the X-axis and the Z-axis.
While the dispenser supplies electrically conductive paste 28 on the intaglio plate 27, the doctor blade 23 is slid along the X-axis on the intaglio plate 27 to fill the intaglio patterns 26 on the intaglio plate 27 with the electrically conductive paste 28. The electrically conductive paste 28 that fills in the intaglio patterns 26 is received by the transfer roller 24, and the printing patterns held by the transfer roller 24 are transferred to the substrate 11. The printing patterns transferred to the substrate 11 are cured by heating, thus completing the net-like electrodes 12, the outer-edge wiring lines 13, and the connection wiring lines 14 of the touch sensor 10.